The purpose of this study is to determine whether treatment with inhibitors of cytokine production (thalidomide) or of HIV replication (combinations of potent anti-retroviral agents) will ameliorate anorexia, metabolic alterations, and consequent loss of weight and lean body mass in HIV-infected patients with an acute systemic infection (P. carinii pneumonia). Measurements of energy intake, body weight and composition, resting and total daily energy expenditure, substrate metabolism, HIV RNA and cytokine levels, and quality of life will be obtained in two separate double-blind placebo-controlled out-patient trials in which patients receiving standardized therapy for PCP will be randomly assigned to either 1). treatment with thalidomide or placebo; or 2). potent combinations of antiretroviral agents or placebo.